There is a long history trying to convert lignin from ligno-cellulosic (lignocellulosic) biomass into useful components. Three categories of lignin isolation from biomass can be broadly classified.
The first is the Organosolv process which extracts the lignin with organic solvents and then treats the extracted lignin. The drawback of this process is the presence and use of organic solvents which must later be removed from the products.
The second is the various Kraft processes used in the paper and pulp industry. Kraft lignin has been extracted from the ligno-cellulosic biomass using acids and bases and thus requiring removal and neutralization of the excess acids and bases.
The third is the base depolymerization of the lignin, again attacking the lignin and leaving the base as a contaminant to deal with.
However, with the advent of second generation biomass facilities, the lignin containing by-product streams contain high amounts of water, cellulose, and lignin as opposed to the first generation facilities which relied upon purified starches from grains as the sugar(s) for fermentation, leaving very little lignin.
The second generation processes remove the sugars from the ligno-cellulosic polymers, in particular, the C6 sugars which are known to be harder to extract and convert to the respective oligomer and monomers. In any event, the second generation systems typically ferment the sugars in the presence of the lignin, with the lignin being present in a by-product stream with a high water content.
There exists therefore the need for a process to convert the lignin from second generation ligno-cellulosic biomass conversion process to usable compounds.